Tank Jacket Steam Control

[Guest rkduet]

I have a project utilizing snap acting steam control valve on tank jacket. I currently have programmed a preact for course heat controlled by campare instructions. Then once course preact temp is reached around 5.6 degrees preact from setpoint. Then a fine heat cycle controlled by compares and cycle timer with differential. Is there a better way to achieve setpoint with snap acting valve? I should add that once preact is reached and the valve is shut the temp creeeps and settles to setpoint. The cycle timer and fine routine is used to try to maitain temp. The PLC is an AB MicroLogix 1200 series C.

[Guest Guest_Peter Nachtwey]

See the thread above on PLC PID control. There is a link to an example of sliding mode control which is a formalized version of what you are trying to do.